It's unclear if those seen picking up the jackets, meant for finishers of the race, were aware of what had transpired minutes earlier.

It is clear, however, that some people took more than one.

The video was posted to Reddit.com, where users debated the footage and threatened to shame those in it.

"Take a high quality screenshot of each and every one of their faces," one user wrote. "Make a Tumblr. Plaster each persons face online. Get Reddit to front page it and make it go viral."

The user added, "I honestly wouldn't normally advocate this sort of mob justice, but that one piece of s--- smiling while grabbing all the [jackets] he could carry while people were dying 20 feet away got to me."

"Entirely possible that some of them were doing this for a legitimate reason," another wrote. "Namely, a runner was at the finish line but didn't have access to their belongings due to the bombing and were left in the cold."

"I'm really hoping these people are taking jackets to the injured to cover wounds," another user wrote. "But I know better."

Three people died and 176 others were wounded, 17 critically, in the blasts, officials said Tuesday.